A medical capsule device for releasing a substance at a defined location in the gastrointestinal tract. The device has a capsule body defining one or more apertures in the circumferential wall thereof and a sleeve valve rotatably positioned therein having one or more corresponding apertures in the circumferential...http://www.google.ca/patents/US5170801?utm_source=gb-gplus-sharePatent US5170801 - Medical capsule device actuated by radio-frequency (RF) signal
